Christmas is a pagan Holyday.
It can be if you want it to be.
On the other hand, any day you want to choose to celebrate the birth of our savior is a good day to do so. Pray to God in thanks for the gift of our salvation, and celebrate. Glorify Christ and make a joyful noise.
If you do it on the same day as other belivers, so much the better. The date isn't important, what is in your heart and your purpose is important.
And yes, the son of God was probably not born on December 25th, but so what?
"Santa Claus" day is a pagan holiday, so don't celebrate it if you don't want.